This invention relates to entering information into, and displaying information from a data processor.
One device for displaying such information is the well-known liquid crystal display (LCD) which has a special liquid crystal material held between two parallel glass faces. The liquid crystal material temporarily changes its molecular structure, and thus its appearance, when subjected to an electrical field. Appropriately shaped transparent electrodes printed on the glass faces establish such an electrical field in the liquid crystal material to form a desired image, such as numbers representing the time of day.
One device for entering information into a data processor is a touch pad on which the user "writes" either with his finger, a pen, or a special purpose stylus. Corresponding electrical signals are generated by one of several techniques, including electromagnetic induction, variable capacitance, make-and-break switching, or grids of parallel infrared beams. Some touch pads have soft membrane surfaces which must be depressed to be activated.
The computer may be arranged so that whatever is "written" on the pad is immediately displayed back to the user on the computer's CRT display.
Another data entry technique is the light pen which senses the time at which light appears at a selected spot on a scanned display screen as an indication of the location of the spot.